Mitsubishi Galant. Manual — part 689

SWS DIAGNOSIS

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-151

CIRCUIT OPERATION.
When the fog light switch is turned on while the front-
ECU is illuminating the taillights or headlights (low-
beam), the ETACS-ECU sends a `light on' signal to
the front-ECU, causing the front-ECU to illuminate
the fog lights.

TECHNICAL DESCRIPTION (COMMENT)
If the taillights and headlights illuminate normally, the
fog light relay, the fog light switch, the front-ECU or
the ETACS-ECU may be defective.

NOTE: If only one of the fog lights or the fog light
indicator light does not illuminate, the relevant bulb
may be burned out or the harness wire between the
defective light and the fog light relay may be
defective. In this case, check the relevant circuit by
referring to GROUP 90, Fog Light

P.90-68

.

TROUBLESHOOTING HINTS

•

Malfunction of the fog light relay

•

Malfunction of the fog light switch

•

Malfunction of the front-ECU

•

Malfunction of the ETACS-ECU

•

Damaged harness wires or connectors

DIAGNOSIS

Required Special Tools:

•

MB991223: Test Harness Set

•

MB991502: Scan Tool (MUT-II)

•

MB991529: Diagnostic Trouble Code Check Harness

AC003128 AK

A-09X

CONNECTORS: A-06X, A-09X

FRONT - ECU

A-06X

FOGLIGHT
RELAY

BATTERY

AC003129 AK

A-31

CONNECTORS: A-28, A-31

A-28

AC003089 AF

CONNECTORS: C-05, C-29

C-29

C-05

AC003079 AB

CONNECTOR
BLOCK (LH)

CONNECTOR: C-66

AC003082 AM

CONNECTORS: C-73, C-78

C-73

C-78

JUNCTION BLOCK
(FRONT VIEW)

SWS DIAGNOSIS

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-152

STEP 1. Check the taillights and headlight operation.

Q: Do the taillights and headlights illuminate normally?

YES : Go to Step 2 <when using scan tool MB991502> or 3

<when using a voltmeter>.

NO : Solve the problem first. Refer to

P.54B-9

.

STEP 2. Check the input signal (by using scan tool
MB991502).
Check the input signals from the fog light switch.

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK" (OFF) position before
connecting or disconnecting scan tool MB991502.
(1)Connect scan tool MB991502 to the data link connector.
(2)Check that the tone alarm of scan tool MB991502 sounds

when the input signal enters.

Q: Does the tone alarm of scan tool MB991502 sound when

the input signal enters?
YES : Go to Step 4.
NO : Check the fog light input signal circuit. Refer to

Inspection Procedure N-5 (

P.54B-194

).

STEP 3. Check the input signal (by using a voltmeter).
Check the input signals from the fog light switch.
(1)Use special tool MB991529 to connect a voltmeter between

ground terminal 4 or 5 and ETACS-ECU terminal 9 of the
data link connector.

(2)Check that the voltmeter indicator deflects once when the

input signal enters.

Q: Does the voltmeter indicator deflect?

YES : Go to Step 4.
NO : Check the fog light input signal circuit. Refer to

Inspection Procedure N-5 (

P.54B-194

).

STEP 4. Check the fog light relay.

Q: Is the fog light relay in good condition?

YES : Go to Step 5.
NO : Replace it. The fog lights should illuminate normally.

AC003081 AB

16 PIN

MB991502

AC003083

16 PIN

AB

ETACS-ECU
TERMINAL

GROUNDED TERMINAL

MB991529

BATTERY
VOLTAGE

TESTER
CONNECTION

SPECIFIED
CONDITION

Not applied

1

−

3

Continuity

1

−

Battery (+)

terminal,
3

−

Battery (

−

)

terminal

4

−

5

Continuity

1

2 3

4

5

1

3

4

5

ACX01544

SWS DIAGNOSIS

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-153

STEP 5. Check the fog light relay power supply circuit at
the fog light relay connector A-06X.
(1)Disconnect the fog light relay connector A-06X and

measure at the relay box side.

(2)Measure the voltages between terminal 1, 4 and ground.

Q: Are the voltages approximately 12 volts (battery

positive voltage)?
YES : Go to Step 8.
NO : Go to Step 6.

STEP 6. Check fog light relay connector A-06X for damage.
Q: Is fog light relay connector A-06X in good condition?

YES : Go to Step 7.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. The fog lights should

illuminate normally.

STEP 7. Check the harness wire between fog light relay
connector A-06X and battery.
Q: Is the harness wire between fog light relay connector A-

06X and battery in good condition?
YES : There is no action to be taken.
NO : Repair it. The fog lights should illuminate normally.

1

2

3

4

5

AC002142 AB

CONNECTOR A-06X
(RELAY BOX SIDE)

AC003128 AL

CONNECTOR: A-06X

FOGLIGHT
RELAY

BATTERY

AC003128 AL

CONNECTOR: A-06X

FOGLIGHT
RELAY

BATTERY

SWS DIAGNOSIS

TSB Revision

SIMPLIFIED WIRING SYSTEM (SWS)

54B-154

STEP 8. Check fog light relay connector A-06X and front-
ECU connector A-09X for damage.
Q: Are fog light relay connector A-06X and front-ECU

connector A-09X in good condition?
YES : Go to Step 9.
NO : Repair or replace them. Refer to GROUP 00E,

Harness Connector Inspection

P.00E-2

. The fog

lights should illuminate normally.

STEP 9. Check the harness wire between fog light relay
connector A-06X and front-ECU connector A-09X.
Q: Is the harness wire between fog light relay connector A-

06X and front-ECU connector A-09X in good condition?
YES : Go to Step 10.
NO : Repair it. The fog lights should illuminate normally.

STEP 10. Check fog light connectors A-28 and A-31 and
combination meter connector C-29 for damage.
Q: Are fog light connectors A-28 and A-31 and combination

meter connector C-29 in good condition?
YES : Go to Step 11.
NO : Repair or replace them. Refer to GROUP 00E,

Harness Connector Inspection

P.00E-2

. The fog

lights should illuminate normally.

AC003128 AK

A-09X

CONNECTORS: A-06X, A-09X

FRONT - ECU

A-06X

FOGLIGHT
RELAY

BATTERY

AC003128 AK

A-09X

CONNECTORS: A-06X, A-09X

FRONT - ECU

A-06X

FOGLIGHT
RELAY

BATTERY

AC003129 AK

A-31

CONNECTORS: A-28, A-31

A-28

AC003089 AD

CONNECTOR: C-29